Sultan Ahmed Sanjar died in 1156. As the Seljuk state fell into chaos, the Khwarezm-Shahs expanded their territories southward. In 1194, the last Sultan of the Great Seljuq Empire, Toghril III, was defeated and killed by the Khwarezm ruler Ala ad-Din Tekish, who conquered parts of Khorasan and western Iran. In 1200, Tekish died and was succeeded by his son, Ala ad-Din Muhammad, who initiated a conflict with the Ghurids and was defeated by them at Amu Darya (1204).[15] Following the sack of Khwarizm, Muhammad appealed for aid from his suzerain, the Kara Khitai who sent him an army.[16] With this reinforcement, Muhammad won a victory over the Ghorids at Hezarasp (1204) and forced them out of Khwarizm. Muhammad's gratitude towards his suzerain was short-lived. He again initiated a conflict, this time with the aid of the Kara-Khanids, and defeated a Kara-Khitai army at Talas (1210),[17] but allowed Samarkand (1210) to be occupied by the Kara-Khitai.[18] He overthrew the Karakhanids (1212)[19] and Ghurids (1215). In 1212, Muhammad II shifted capital from Gurganj to Samarkand. Thus Muhammad II incorporated nearly the whole of Transoxania[citation needed] and present-day Afghanistan into his empire, which after further conquests in western Persia (by 1217) stretched from the Syr Darya to the Zagros Mountains, and from the Indus Valley to the Caspian Sea.

War and collapse

In 1218, Genghis Khan sent a trade mission to the state, but at the town of Otrar the governor, suspecting the Khan's ambassadors to be spies, confiscated their goods and executed them. Genghis Khan demanded reparations, which the Shah refused to pay. Genghis retaliated with a force of 200,000 men, launching a multi-pronged invasion. In February 1220 the Mongolian army crossed the Syr Darya, beginning the Mongol invasion of Central Asia. The Mongols stormed Bukhara, Gurganj and the Khwarezmid capital Samarkand. The Shah fled and died some weeks later on an island in the Caspian Sea.

In Great Captains Unveiled of 1927, B.H. Liddell Hart gave details of the Mongol campaign against Khwarezm, underscoring his own philosophy of "the indirect approach," and highlighting many of the tactics used by Genghis which were to be subsequently included in the Blitzkrieg tactics employed less than two decades later by Nazi Germany.[20]

Mercenaries

Though the Mongols had destroyed the Khwarezmian Empire in 1220, many Khwarezmians survived by working as mercenaries in northern Iraq. Sultan Jalal ad-Din's followers remained loyal to him even after his death in 1231, and raided the Seljuk lands of Jazira and Syria for the next several years, calling themselves the Khwarezmiyya. Ayyubid Sultan as-Salih Ayyub, in Egypt, later hired their services against his uncle as-Salih Ismail. The Khwarezmiyya, heading south from Iraq towards Egypt, invaded Crusader Christian-held Jerusalem along the way, on July 11, 1244. The city's citadel, the Tower of David, surrendered on August 23, the Crusader Christian population of the city was expelled. This triggered a call from Europe for the Seventh Crusade, but the Crusaders would never again be successful in retaking Jerusalem. After being conquered by the Khwarezmian forces, the city stayed under Muslim control until 1917, when it was taken from the Ottomans by the British.

After taking Jerusalem, the Khwarezmian forces continued south, and on October 17 fought on the side of the Ayyubids at the Battle of Harbiyah, northeast of Gaza, killing the remains of the Crusader Christian army there, some 1,200 knights. It was the largest battle involving the crusaders since the Battle of the Horns of Hattin in 1187.[22]

The remains of the Muslim Khwarezmians served in Egypt as Mamluk mercenaries until they were finally beaten by al-Mansur Ibrahim some years later.

Khwarizmi war captives assimilated into the Mongols, forming the modern Mongolian clan Sartuul.

^C. E. Bosworth: KHWARAZMSHAHS i. Descendants of the line of Anuštigin. In Encyclopaedia Iranica, online ed., 2009: "Little specific is known about the internal functioning of the Khwarazmian state, but its bureaucracy, directed as it was by Persian officials, must have followed the Saljuq model. This is the impression gained from the various Khwarazmian chancery and financial documents preserved in the collections of enšāʾdocuments and epistles from this period. The authors of at least three of these collections—Rašid-al-Din Vaṭvāṭ (d. 1182-83 or 1187-88), with his two collections of rasāʾel, and Bahāʾ-al-Din Baḡdādi, compiler of the important Ketāb al-tawaṣṣol elā al-tarassol—were heads of the Khwarazmian chancery. The Khwarazmshahs had viziers as their chief executives, on the traditional pattern, and only as the dynasty approached its end did ʿAlāʾ-al-Din Moḥammad in ca. 615/1218 divide up the office amongst six commissioners (wakildārs; see Kafesoğlu, pp. 5-8, 17; Horst, pp. 10-12, 25, and passim). Nor is much specifically known of court life in Gorgānj under the Khwarazmshahs, but they had, like other rulers of their age, their court eulogists, and as well as being a noted stylist, Rašid-al-Din Vaṭvāṭ also had a considerable reputation as a poet in Persian."

^Homa Katouzian, "Iranian history and politics", Published by Routledge, 2003. pg 128: "Indeed, since the formation of the Ghaznavids state in the tenth century until the fall of Qajars at the beginning of the twentieth century, most parts of the Iranian cultural regions were ruled by Turkic-speaking dynasties most of the time. At the same time, the official language was Persian, the court literature was in Persian, and most of the chancellors, ministers, and mandarins were Persian speakers of the highest learning and ability"

^"Persian Prose Literature." World Eras. 2002. HighBeam Research. (September 3, 2012);"Princes, although they were often tutored in Arabic and religious subjects, frequently did not feel as comfortable with the Arabic language and preferred literature in Persian, which was either their mother tongue—as in the case of dynasties such as the Saffarids (861–1003), Samanids (873–1005), and Buyids (945–1055)—or was a preferred lingua franca for them—as with the later Turkish dynasties such as the Ghaznawids (977–1187) and Saljuks (1037–1194)". [1]

^C. E. Bosworth, "CHORASMIA ii. In Islamic times" in: Encyclopaedia Iranica (reference to Turkish scholar Kafesoğlu), v, p. 140, Online Edition: "The governors were often Turkish slave commanders of the Saljuqs; one of them was Anūštigin Ḡaṛčaʾī, whose son Qoṭb-al-Dīn Moḥammad began in 490/1097 what became in effect a hereditary and largely independent line of ḵǰᵛārazmšāhs." (LINK)

^Rene Grousset, The Empire of the Steppes:A History of Central Asia, Transl. Naomi Walford, (Rutgers University Press, 1991), 159.

^Biran, Michel, The Empire of the Qara Khitai in Eurasian history, (Cambridge University Press, 2005), 44.